Light from a plurality of light emitting diodes (LEDs) of different colors (e.g., red, green and blue) has been used to create a light source of predetermined spectral balance (e.g., a “white” light source). See, for example, the U.S. Pat. No. 6,448,550 of Nishimura entitled “Method and Apparatus for Measuring Spectral Content of LED Light Source and Control Thereof”.